This proposal describes a five year training program for the development of an academic career in molecular cardiology as it pertains to regulation of endothelial cell differentiation, angiogenesis and embryogenesis by RhoGAP proteins. The principal investigator has completed three years of postdoctoral training in molecular cardiology in addition to a two-year clinical cardiology training, and he is currently board eligible in cardiology. This program provides a unique opportunity to build on the principal investigator's clinical and molecular biology expertise and to combine structured learning, course work and laboratory techniques into a multidisciplinary approach to studying the molecular, genomic and physiologic regulation of endothelial cell differentiation by p68RacGAP under the tutelage of Dr. Cam Patterson, Professor of Medicine who is internationally recognized as a leader in the field of endothelial cell differentiation. To enhance the training, the program has enlisted the expertise of an advisory committee that consists of established investigators with expertise in molecular biology for scientific and career advice, and the assistance of collaborators with extensive expertise and experience in the field of cell biology, angiogenesis, and targeted inactivation of genes. The proposed research will focus on the role of p68RacGAP, identified via its in vivo interaction with an endothelial cell-specific transcription factor (Vezfl), in regulation of endothelial cell differentiation, angiogensis and embryogenesis. We have shown that p68RacGAP is a Rac1-specific RhoGAP protein that inhibits endothelial cell capillary assembly in vivo. We hypothesize that p68RacGAP is a regulatory protein that is critical to endothelial cell differentiation and angiogenesis and that targeted deletion of p68RacGAP gene will lead to perturbation in embryogenesis. The overall objectives of this proposal are to define the biologic effect of p68RacGAP-dependent signal regulation on endothelial cell differentiation, determine the role of p68RacGAP on angiogenesis and to characterize the phenotype of p68RacGAP knockout mice and analyze targeted embryos for vascular and cardiac defects by immunohistochemical analysis and functional assays. The University of North Carolina-Chapel Hill Department of Internal Medicine and the Carolina Cardiovascular Biology Center provides an ideal training environment for physician-scientists by its diverse resources, established investigators, and support for young investigators. (End of Abstract)